Imaging system

ABSTRACT

A three-dimensional imaging system to reduce detected ambient light comprises a wavelength stabilized laser diode to project imaging light onto a scene, an optical bandpass filter, and a camera to receive imaging light reflected from the scene and through the optical bandpass filter, the camera configured to use the received imaging light for generating a depth map of the scene.

BACKGROUND

Three-dimensional imaging systems utilize depth cameras to capture depthinformation of a scene. The depth information can be translated to depthmaps in order to three-dimensionally map objects within the scene. Somedepth cameras use projected infrared light to determine depth of objectsin the imaged scene. Accurate determination of the depth of objects inthe scene can be hindered when excess ambient light in the scenedisrupts the camera's ability to receive the projected infrared light.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

A 3-D imaging system for blocking ambient light is disclosed. The systemincludes a passively-cooled wavelength stabilized laser diode to projectimaging light onto a scene, an optical bandpass filter having atransmission range less than 20 nm full width at half maximum, and acamera to receive the imaging light reflected from the scene and throughthe optical bandpass filter. The wavelength stabilized laser diode mayinclude a frequency selective element to stabilize the wavelength ofprojected imaging light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a three-dimensional imaging system viewing an observedscene in accordance with an embodiment of the present disclosure.

FIG. 2 somewhat schematically shows the modeling of a human target witha virtual skeleton.

FIGS. 3-4 show various embodiments of a capture device according to thepresent disclosure.

FIG. 5 schematically shows a nonlimiting computing system.

FIG. 6 shows a wavelength stabilized laser diode in accordance with anembodiment of the present disclosure.

FIG. 7 shows another wavelength stabilized laser diode in accordancewith an embodiment of the present disclosure.

DETAILED DESCRIPTION

A three-dimensional imaging system, such as a 3D-vision gaming system,may include a depth camera capable of observing objects within a scene.As one example, a depth camera can observe game players as they play agame. As the depth camera captures images of a player within an observedscene (i.e., the imaged scene in the field of view of the depth camera),those images may be interpreted and modeled with one or more virtualskeletons. As described in more detail below, excess ambient light maycause problems with the depth images captured by the depth cameraleading to areas of invalid depth information in the depth images. Thiscan disrupt imaging and subsequent modeling of the player.

FIG. 1 shows a nonlimiting example of a three-dimensional imaging system10. In particular, FIG. 1 shows a gaming system 12 that may be used toplay a variety of different games, play one or more different mediatypes, and/or control or manipulate non-game applications and/oroperating systems. FIG. 1 also shows a display device 14 such as atelevision or a computer monitor, which may be used to present gamevisuals to game players. As one example, display device 14 may be usedto visually present a virtual avatar 16 that human target 18 controlswith his movements. The 3-D imaging system 10 may include a capturedevice, such as a depth camera 22, that visually monitors or trackshuman target 18 within an observed scene 24. Depth camera 22 isdiscussed in greater detail with respect to FIGS. 2 and 3.

Human target 18 is shown here as a game player within observed scene 24.Human target 18 is tracked by depth camera 22 so that the movements ofhuman target 18 may be interpreted by gaming system 12 as controls thatcan be used to affect the game being executed by gaming system 12. Inother words, human target 18 may use his or her movements to control thegame. The movements of human target 18 may be interpreted as virtuallyany type of game control. Some movements of human target 18 may beinterpreted as controls that serve purposes other than controllingvirtual avatar 16. Movements may also be interpreted as auxiliary gamemanagement controls. For example, human target 18 may use movements toend, pause, save, select a level, view high scores, communicate withother players, etc.

Depth camera 22 may also be used to interpret target movements asoperating system and/or application controls that are outside the realmof gaming. Virtually any controllable aspect of an operating systemand/or application may be controlled by movements of a human target 18.The illustrated scenario in FIG. 1 is provided as an example, but is notmeant to be limiting in any way. To the contrary, the illustratedscenario is intended to demonstrate a general concept, which may beapplied to a variety of different applications without departing fromthe scope of this disclosure.

The methods and processes described herein may be tied to a variety ofdifferent types of computing systems. FIG. 1 shows a nonlimiting examplein the form of gaming system 12, display device 14, and depth camera 22.In general, a 3-D imaging system may include a computing system 300,shown in simplified form in FIG. 5, which will be discussed in greaterdetail below.

FIG. 2 shows a simplified processing pipeline in which human target 18in an observed scene 24 is modeled as a virtual skeleton 32 that can beused to draw a virtual avatar 16 on display device 14 and/or serve as acontrol input for controlling other aspects of a game, application,and/or operating system. It will be appreciated that a processingpipeline may include additional steps and/or alternative steps thanthose depicted in FIG. 2 without departing from the scope of thisdisclosure.

As shown in FIG. 2, human target 18 and the rest of observed scene 24may be imaged by a capture device such as depth camera 22. The depthcamera may determine, for each pixel, the depth of a surface in theobserved scene relative to the depth camera. Virtually any depth findingtechnology may be used without departing from the scope of thisdisclosure. For example, structured light or time-of-flight depthfinding technologies may be used. Example depth hardware is discussed inmore detail with reference to capture device 310 of FIG. 5.

The depth information determined for each pixel may be used to generatea depth map 30. Such a depth map may take the form of virtually anysuitable data structure, including but not limited to a matrix thatincludes a depth value for each pixel of the observed scene. In FIG. 2,depth map 30 is schematically illustrated as a pixelated grid of thesilhouette of human target 18. This illustration is for simplicity ofunderstanding, not technical accuracy. It is to be understood that adepth map generally includes depth information for all pixels, not justpixels that image the human target 18, and that the perspective of depthcamera 22 would not result in the silhouette depicted in FIG. 2.

Virtual skeleton 32 may be derived from depth map 30 to provide amachine readable representation of human target 18. In other words,virtual skeleton 32 is derived from depth map 30 to model human target18. The virtual skeleton 32 may be derived from the depth map in anysuitable manner. In some embodiments, one or more skeletal fittingalgorithms may be applied to the depth map. The present disclosure iscompatible with virtually any skeletal modeling techniques.

The virtual skeleton 32 may include a plurality of joints, each jointcorresponding to a portion of the human target. In FIG. 2, virtualskeleton 32 is illustrated as a fifteen-joint stick figure. Thisillustration is for simplicity of understanding, not technical accuracy.Virtual skeletons in accordance with the present disclosure may includevirtually any number of joints, each of which can be associated withvirtually any number of parameters (e.g., three dimensional jointposition, joint rotation, body posture of corresponding body part (e.g.,hand open, hand closed, etc.) etc.). It is to be understood that avirtual skeleton may take the form of a data structure including one ormore parameters for each of a plurality of skeletal joints (e.g., ajoint matrix including an x position, a y position, a z position, and arotation for each joint). In some embodiments, other types of virtualskeletons may be used (e.g., a wireframe, a set of shape primitives,etc.).

As shown in FIG. 2, a virtual avatar 16 may be rendered on displaydevice 14 as a visual representation of virtual skeleton 32. Becausevirtual skeleton 32 models human target 18, and the rendering of thevirtual avatar 16 is based on the virtual skeleton 32, the virtualavatar 16 serves as a viewable digital representation of the humantarget 18. As such, movement of virtual avatar 16 on display device 14reflects the movements of human target 18.

In some embodiments, only portions of a virtual avatar will be presentedon display device 14. As one nonlimiting example, display device 14 maypresent a first person perspective to human target 18 and may thereforepresent the portions of the virtual avatar that could be viewed throughthe virtual eyes of the virtual avatar (e.g., outstretched hands holdinga steering wheel, outstretched arms holding a rifle, outstretched handsgrabbing a virtual object in a three-dimensional virtual world, etc.).

While virtual avatar 16 is used as an example aspect of a game that maybe controlled by the movements of a human target via the skeletalmodeling of a depth map, this is not intended to be limiting. A humantarget may be modeled with a virtual skeleton, and the virtual skeletoncan be used to control aspects of a game or other application other thana virtual avatar. For example, the movement of a human target cancontrol a game or other application even if a virtual avatar is notrendered to the display device.

Returning to FIG. 1, an example embodiment is shown depicting one ormore sources of ambient light that can result in invalid depthinformation in the depth image. Window 26 is allowing sunlight to enterthe observed scene 24. In addition, lamp 28 is on. Excess light in theimaged scene can overwhelm the projected infrared light that the depthcamera uses to determine depth of surfaces in the scene, reducing thedistance at which the depth camera can accurately model the virtualskeleton.

Embodiments of a 3-D imaging system to reduce the amount of ambientlight received at a capture device will now be described with respect toFIGS. 3 and 4. Turning to FIG. 3, an actively cooled capture device 102designed to block a very large spectrum of ambient light is shown.Capture device 102 includes a depth camera 104 configured to use imaginglight to generate a depth map (e.g., depth map 30 of FIG. 2). The depthcamera 104 may use any suitable method to analyze the received imaginglight, such as time of flight analysis or structured light analysis.

The depth camera 104 may itself be configured to generate a depth mapfrom the received imaging light. The depth camera 104 may thus includean integrated computing system (e.g., computing system 300 shown of FIG.5). The depth camera 104 may also comprise an output (not shown) foroutputting the depth map, for example to a gaming or display device.Alternatively, the computing system 300 may be located remotely from thedepth camera 104 (e.g., as part of a gaming console), and the computingsystem 300 may receive parameters from the depth camera 104 in order togenerate a depth map.

As described above, accurate modeling of a virtual skeleton by the depthcamera 104 can be confounded by excess ambient light received at thedepth camera 104. To reduce the ambient light received at the depthcamera 104, capture device 102 includes components to restrict thewavelength of light received at the depth camera 104, including awavelength stabilized laser diode 106 and a temperature controller 108.An optical bandpass filter 110 is also included to pass the wavelengthof the laser diode to the sensor and block other wavelengths of lightpresent in the scene, such as ambient light.

To project imaging light onto a scene, the capture device 102 includes awavelength stabilized laser diode 106 for projecting infrared light. Thewavelength stabilized laser diode 106 may be coupled to the depth camera104 in one embodiment, while in other embodiments it may be separate.Standard, non-stabilized laser diodes, referred to as Fabre-Perot laserdiodes, may undergo temperature-dependent wavelength changes that resultin light being emitted in a broad range of wavelengths as lasertemperature varies. Thus it is required to include expensive activecooling to limit the range of wavelengths emitted by the laser diode. Incontrast, the wavelength stabilized laser diode 106 may be configured toemit light in a relatively narrow wavelength range that remains stableas a temperature of the laser diode changes. In some embodiments, thewavelength stabilized laser diode 106 may be tuned to emit light in arange of 824 to 832 nm, although other ranges are within the scope ofthis disclosure.

Stabilization of the wavelength stabilized laser diode 106 may beachieved by a frequency selective element that resonates light in anarrow window. For example, the frequency selective element maystabilize the laser diode such that the light emitted by the laserchanges by less than 0.1 nm for each 1° C. change in laser diodetemperature. In one embodiment, the wavelength stabilized laser diode106 may include a distributed bragg reflector laser 120, discussed inmore detail with reference to FIG. 6 below. In some embodiments, thewavelength stabilized laser diode 106 may include a distributed feedbacklaser 122, discussed in more detail with reference to FIG. 7. Anyfrequency selective element that stabilizes the wavelength of lightemitted from the wavelength stabilized laser diode 106 is within thescope of this disclosure.

FIGS. 6 and 7 schematically show two example frequency selectiveelements according to the present disclosure. FIG. 6 schematically showsa distributed bragg reflector laser 120 including an active medium 402with at least one corrugated grating 404 coupled to at least one end ofthe active medium 402. The corrugated grating 404 provides opticalfeedback to the laser to restrict light emission to a relatively narrowwavelength window. As light propagates from and through the activemedium 402, it is reflected off the corrugated grating 404. Thefrequency and/or amplitude of the corrugated grating 404 determines thewavelength of reflected light.

The corrugated grating 404 can be made from but is not limited tomaterials typically found in the construction of the laser diode. Whileone corrugated grating is shown, distributed bragg reflector laser 120may include two corrugated gratings with the active medium 402positioned between the gratings. The active medium 402 may include anysuitable semiconducting substance such as gallium arsenide, indiumgallium arsenide, or gallium nitride.

FIG. 7 schematically shows a distributed feedback laser 122 alsoincluding a corrugated grating 414 coupled to an active medium 412. Incontrast to the distributed bragg reflector laser 120, distributedfeedback laser 122 has the active medium 412 and the corrugated grating414 integrated into one unit.

Returning to FIG. 3, to further stabilize the wavelength of lightemitted by the wavelength stabilized laser diode 106, the capture device102 may include a temperature controller 108 coupled to the wavelengthstabilized laser diode 106. The temperature controller 108 activelycools the wavelength stabilized laser diode 106 and includes athermoelectric cooler 112, or Peltier device, coupled to the wavelengthstabilized laser diode 106 to pump heat from the wavelength stabilizedlaser diode 106 to a heat sink 114. When current runs through thethermoelectric cooler 112, heat is transferred from the laser diode 106to the heat sink 114 and dissipated into air via a fan 118. Athermocouple 116, which may be coupled to the thermoelectric cooler 112and the heat sink 114, can determine a temperature of the thermoelectriccooler 112 and/or heat sink 114, and may control activation of the fan118 and/or thermoelectric cooler 112 to maintain the wavelengthstabilized laser diode 106 within a predetermined temperature range.

The wavelength stabilized laser diode 106 may be thermally controlled bythe temperature controller 108 within a broad range of ambienttemperatures. For example, the capture device 102 may be operated in anenvironment having a temperature range of 5 to 40° C., and therefore thewavelength stabilized laser diode 106 may be configured to remain stableat any temperature in that range. Further, the wavelength stabilizedlaser diode 106 may be controlled by the temperature controller 108 toremain within 1° C. of a predetermined set temperature. Thus, even as anambient environment around the wavelength stabilized laser diode 106increases in temperature, the temperature controller 108 can maintainthe wavelength stabilized laser diode 106 at a set temperature toprovide further stabilization of the emitted light. For example, thewavelength stabilized laser diode 106 may be actively cooled to remainin a range of 40 to 45° C., or another suitable temperature range.

The combination of the frequency selective element in the wavelengthstabilized laser diode 106 and the temperature controller 108 coupled tothe wavelength stabilized laser diode 106 act to narrowly restrict thewavelength of emitted imaging light, and thus narrowly restrict thewavelength of the reflected imaging light. However, before beingreceived at the depth camera 104, the reflected imaging light may firstpass through an optical bandpass filter 110 coupled to the depth camera104 and configured to block substantially all light other than theimaging light.

The optical bandpass filter 110 may allow transmission of a narrow rangeof light in order to reduce the transmission of ambient light. Toaccomplish this, the optical bandpass filter 110 may be comprised of amaterial, such as colored glass, that transmits light in a wavelengthrange that matches the wavelength of the imaging light. As one example,the optical bandpass filter 110 may have a transmission range of lessthan 15 nm full width at half maximum (FWHM). That is, the opticalbandpass filter 110 may allow transmission of light of a predeterminedwavelength, as well as a 15 nm “window” on either side of thatwavelength.

As the transmission range of the optical bandpass filter 110 narrows, sotoo does the wavelength range of light received at the depth camera 104.As such, in some embodiments, the capture device 102 may be configuredwith an optical bandpass filter 110 that has a transmission range aswide as the variation of light emitted from the wavelength stabilizedlaser diode 106. For example, the optical bandpass filter 110 may have atransmission range no greater than 5 nm FWHM, or it may have atransmission range no greater than 2 nm FWHM.

Together, the wavelength stabilized laser diode 106, temperaturecontroller 108, and optical bandpass filter 110 enable the capturedevice 102 to block a large amount of ambient light from reaching thedepth camera 104. In particular, the active cooling of temperaturecontroller 108 maintains the wavelength of light emitted from wavelengthstabilized laser diode 106 to a narrower range than would be possiblewithout active cooling. Consequently, the bandpass filter 110 can be setto pass only a very narrow range of wavelengths corresponding to thetightly controlled laser. Therefore, a very large portion of ambientlight is blocked from depth camera 104, thus allowing the depth camerato more accurately model an observed scene.

Turning to FIG. 4, an embodiment of a passively cooled capture device202 configured to block ambient light is shown. Similar to the capturedevice 102, the capture device 202 includes a depth camera 204configured to use imaging light to generate a depth map and a wavelengthstabilized laser diode 206 to project the imaging light. In oneembodiment, the wavelength stabilized laser diode 206 may include adistributed bragg reflector laser 220, while in some embodimentswavelength stabilized laser diode 206 may include a distributed feedbacklaser 222.

In contrast to the capture device 102 described with respect to FIG. 3,the capture device 202 includes a passive cooling system coupled to thewavelength stabilized laser diode 206. The passive cooler comprises aheat sink 208 thermally coupled to the wavelength stabilized laser diode206 without an intermediate Peltier device. In this way, heat generatedby the wavelength stabilized laser diode 206 may be passed to the heatsink 208. However, this passive cooling system may allow the wavelengthstabilized laser diode 206 to operate over a wider temperature rangethan the active temperature controller 108 and wavelength stabilizedlaser diode 106, resulting in a wider range of light emitted from thewavelength stabilized laser diode 206. Nonetheless, the passive coolingsystem may be less expensive, and allow the wavelength stabilized laserto project light with an acceptable range of wavelengths.

In order to expedite the wavelength stabilized laser diode 206 start upin cool ambient temperatures, a heater 210 may be thermally coupled tothe wavelength stabilized laser diode 206 without an intermediatePeltier device. The heater 210 may be thermally coupled to the laserdiode 206 instead of or in addition to the heat sink 208. The heater 210may be activated in response to a thermocouple 212, coupled to thewavelength stabilized laser diode 206, indicating a temperature of thewavelength stabilized laser diode 206 is below a threshold.

The capture device 202 includes an optical bandpass filter 214 coupledto the depth camera 204. The optical bandpass filter 214 may have awider transmission range than the optical bandpass filter 110 of theembodiment described with reference to FIG. 3 to compensate for thewider range of light emitted by the wavelength stabilized laser diode206. The optical bandpass filter 214 may have a transmission rangegreater than 5 nm FWHM and less than 20 nm FWHM. In some embodiments,the optical bandpass filter 214 may have a transmission range of lessthan or equal to 10 nm at 90% maximum transmission. In general, theoptical bandpass filter 214 may be configured to allow the imaging lightemitted from the wavelength stabilized laser diode 206 to pass to thedepth camera 204 while blocking most ambient light present in the imagedscene.

The above described embodiments may each have specific advantages. Forexample, the capture device 102 described in reference to FIG. 3, wherethe laser diode is actively temperature controlled, may provide veryprecise control over the range of the wavelength of light emitted fromthe wavelength stabilized laser diode 106. In turn, the bandpass filter110 may have a narrow transmission range, and therefore a substantialamount of ambient light may be prevented from reaching the depth camera104. On the other hand, the passively cooled system may be less costlythan the actively controlled system, and therefore of more practical usefor certain applications.

In some embodiments, the above described methods and processes may betied to a computing system including one or more computers. Inparticular, the methods and processes described herein may beimplemented as a computer application, computer service, computer API,computer library, and/or other computer program product.

FIG. 5 schematically shows a nonlimiting computing system 300 that mayperform one or more of the above described methods and processes.Computing system 300 is shown in simplified form. It is to be understoodthat virtually any computer architecture may be used without departingfrom the scope of this disclosure. In different embodiments, computingsystem 300 may take the form of a mainframe computer, server computer,desktop computer, laptop computer, tablet computer, home entertainmentcomputer, network computing device, mobile computing device, mobilecommunication device, gaming device, etc.

Computing system 300 includes a logic subsystem 302 and a data-holdingsubsystem 304. Computing system 300 may also optionally include userinput devices such as keyboards, mice, game controllers, cameras,microphones, and/or touch screens, for example.

Logic subsystem 302 may include one or more physical devices configuredto execute one or more instructions. For example, the logic subsystemmay be configured to execute one or more instructions that are part ofone or more applications, services, programs, routines, libraries,objects, components, data structures, or other logical constructs. Suchinstructions may be implemented to perform a task, implement a datatype, transform the state of one or more devices, or otherwise arrive ata desired result.

The logic subsystem may include one or more processors that areconfigured to execute software instructions. Additionally oralternatively, the logic subsystem may include one or more hardware orfirmware logic machines configured to execute hardware or firmwareinstructions. Processors of the logic subsystem may be single core ormulticore, and the programs executed thereon may be configured forparallel or distributed processing. The logic subsystem may optionallyinclude individual components that are distributed throughout two ormore devices, which may be remotely located and/or configured forcoordinated processing. One or more aspects of the logic subsystem maybe virtualized and executed by remotely accessible networked computingdevices configured in a cloud computing configuration.

Data-holding subsystem 304 may include one or more physical,non-transitory, devices configured to hold data and/or instructionsexecutable by the logic subsystem to implement the herein describedmethods and processes. When such methods and processes are implemented,the state of data-holding subsystem 304 may be transformed (e.g., tohold different data).

Data-holding subsystem 304 may include removable media and/or built-indevices. Data-holding subsystem 304 may include optical memory devices(e.g., CD, DVD, HD-DVD, Blu-Ray Disc, etc.), semiconductor memorydevices (e.g., RAM, EPROM, EEPROM, etc.) and/or magnetic memory devices(e.g., hard disk drive, floppy disk drive, tape drive, MRAM, etc.),among others. Data-holding subsystem 304 may include devices with one ormore of the following characteristics: volatile, nonvolatile, dynamic,static, read/write, read-only, random access, sequential access,location addressable, file addressable, and content addressable. In someembodiments, logic subsystem 302 and data-holding subsystem 304 may beintegrated into one or more common devices, such as an applicationspecific integrated circuit or a system on a chip.

FIG. 5 also shows an aspect of the data-holding subsystem in the form ofremovable computer-readable storage media 306, which may be used tostore and/or transfer data and/or instructions executable to implementthe herein described methods and processes. Removable computer-readablestorage media 306 may take the form of CDs, DVDs, HD-DVDs, Blu-RayDiscs, EEPROMs, and/or floppy disks, among others.

It is to be appreciated that data-holding subsystem 304 includes one ormore physical, non-transitory devices. In contrast, in some embodimentsaspects of the instructions described herein may be propagated in atransitory fashion by a pure signal (e.g., an electromagnetic signal, anoptical signal, etc.) that is not held by a physical device for at leasta finite duration. Furthermore, data and/or other forms of informationpertaining to the present disclosure may be propagated by a pure signal.

The terms “module,” “program,” and “engine” may be used to describe anaspect of computing system 300 that is implemented to perform one ormore particular functions. In some cases, such a module, program, orengine may be instantiated via logic subsystem 302 executinginstructions held by data-holding subsystem 304. It is to be understoodthat different modules, programs, and/or engines may be instantiatedfrom the same application, service, code block, object, library,routine, API, function, etc. Likewise, the same module, program, and/orengine may be instantiated by different applications, services, codeblocks, objects, routines, APIs, functions, etc. The terms “module,”“program,” and “engine” are meant to encompass individual or groups ofexecutable files, data files, libraries, drivers, scripts, databaserecords, etc.

It is to be appreciated that a “service”, as used herein, may be anapplication program executable across multiple user sessions andavailable to one or more system components, programs, and/or otherservices. In some implementations, a service may run on a serverresponsive to a request from a client.

As introduced above, the present disclosure may be used with structuredlight or time-of-flight depth cameras. In time-of-flight analysis, thecapture device may emit infrared light to the target and may then usesensors to detect the backscattered light from the surface of thetarget. In some cases, pulsed infrared light may be used, wherein thetime between an outgoing light pulse and a corresponding incoming lightpulse may be measured and used to determine a physical distance from thecapture device to a particular location on the target. In some cases,the phase of the outgoing light wave may be compared to the phase of theincoming light wave to determine a phase shift, and the phase shift maybe used to determine a physical distance from the capture device to aparticular location on the target.

In another example, time-of-flight analysis may be used to indirectlydetermine a physical distance from the capture device to a particularlocation on the target by analyzing the intensity of the reflected beamof light over time, via a technique such as shuttered light pulseimaging.

In structured light analysis, patterned light (i.e., light displayed asa known pattern such as a grid pattern, a stripe pattern, aconstellation of dots, etc.) may be projected onto the target. On thesurface of the target, the pattern may become deformed, and thisdeformation of the pattern may be studied to determine a physicaldistance from the capture device to a particular location on the target.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated may beperformed in the sequence illustrated, in other sequences, in parallel,or in some cases omitted. Likewise, the order of the above-describedprocesses may be changed.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

1. A 3-D imaging system comprising: a passively-cooled wavelengthstabilized laser diode to project imaging light onto a scene, thewavelength stabilized laser diode including a frequency selectiveelement; an optical bandpass filter having a transmission range greaterthan 5 nm full width at half maximum and less than 20 nm full width athalf maximum; and a camera to receive imaging light reflected from thescene and through the optical bandpass filter.
 2. The 3-D imaging systemof claim 1, further comprising a heater thermally coupled to thewavelength stabilized laser diode without an intermediate Peltierdevice.
 3. The 3-D imaging system of claim 2, further comprising athermocouple, wherein the heater is activated in response to thethermocouple indicating a temperature of the wavelength stabilized laserdiode is below a threshold.
 4. The 3-D imaging system of claim 1,further comprising a heat sink thermally coupled to the wavelengthstabilized laser diode without an intermediate Peltier device.
 5. The3-D imaging system of claim 1, wherein the frequency selective elementcomprises a distributed feedback laser.
 6. The 3-D imaging system ofclaim 1, wherein the frequency selective element comprises a distributedbragg reflector.
 7. The 3-D imaging system of claim 1, wherein thewavelength stabilized laser diode is configured to emit light in therange of 824 to 832 nm.
 8. The 3-D imaging system of claim 1, whereinthe bandpass filter has a transmission range of less than or equal to 10nm at 90% maximum transmission.
 9. The 3-D imaging system of claim 1,wherein the wavelength stabilized laser diode is configured to emitlight that changes wavelength by less than 0.1 nm for each 1 degree C.change in laser diode temperature.
 10. A 3-D imaging system comprising:a passively-cooled wavelength stabilized distributed feedback laserdiode to project imaging light onto a scene; an optical bandpass filterhaving a transmission range less than or equal to 10 nm at 90% maximumtransmission; and a camera to receive imaging light reflected from thescene and through the optical bandpass filter.
 11. The 3-D imagingsystem of claim 10, further comprising a heater thermally coupled to thewavelength stabilized laser diode without an intermediate Peltierdevice.
 12. The 3-D imaging system of claim 11, further comprising athermocouple, wherein the heater is activated in response to thethermocouple indicating a temperature of the wavelength stabilized laserdiode is below a threshold.
 13. The 3-D imaging system of claim 10,further comprising a heat sink thermally coupled to the wavelengthstabilized laser diode without an intermediate Peltier device.
 14. The3-D imaging system of claim 10, wherein the optical bandpass filter hasa transmission range greater than 5 nm full width at half maximum andless than 20 nm full width at half maximum.
 15. A 3-D imaging systemcomprising: a passively cooled wavelength stabilized laser diode toproject imaging light onto a scene, the wavelength stabilized laserdiode including a frequency selective element; an optical bandpassfilter having a transmission range greater than 5 nm full width at halfmaximum and less than 20 nm full width at half maximum; a camera toreceive imaging light reflected from the scene and through the opticalbandpass filter; a data-holding subsystem holding instructionsexecutable by a logic subsystem to analyze the imaging light received atthe camera to generate a depth map; and an output for outputting thedepth map.
 16. The 3-D imaging system of claim 15, further comprising aheater thermally coupled to the wavelength stabilized laser diodewithout an intermediate Peltier device.
 17. The 3-D imaging system ofclaim 16, further comprising a thermocouple, wherein the heater isactivated in response to the thermocouple indicating a temperature ofthe wavelength stabilized laser diode is below a threshold.
 18. The 3-Dimaging system of claim 15, further comprising a heat sink thermallycoupled to the wavelength stabilized laser diode without an intermediatePeltier device.
 19. The 3-D imaging system of claim 15, wherein thefrequency selective element comprises a distributed feedback laser. 20.The 3-D imaging system of claim 15, wherein the frequency selectiveelement comprises a distributed Bragg reflector.